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.TH HASH 1 "Jul 17, 2002"
.SH NAME
hash, rehash, unhash, hashstat \- evaluate the internal hash table of the
contents of directories
.SH SYNOPSIS
.LP
.nf
\fB/usr/bin/hash\fR [\fIutility\fR]
.fi

.LP
.nf
\fB/usr/bin/hash\fR [\fB-r\fR]
.fi

.SS "sh"
.LP
.nf
\fBhash\fR [\fB-r\fR] [\fIname\fR]...
.fi

.SS "csh"
.LP
.nf
\fBrehash\fR
.fi

.LP
.nf
\fBunhash\fR
.fi

.LP
.nf
\fBhashstat\fR
.fi

.SS "ksh"
.LP
.nf
\fBhash\fR [\fIname\fR]...
.fi

.LP
.nf
\fBhash\fR [\fB-r\fR]
.fi

.SH DESCRIPTION
.SS "/usr/bin/hash"
.sp
.LP
The \fB/usr/bin/hash\fR utility affects the way the current shell environment
remembers the locations of utilities found.  Depending on the arguments
specified, it adds utility locations to its list of remembered locations or it
purges the contents of the list. When no arguments are specified, it reports on
the contents of the list. The \fB-r\fR option causes the shell to forget all
remembered locations.
.sp
.LP
Utilities provided as built-ins to the shell are not reported by \fBhash\fR.
.SS "sh"
.sp
.LP
For each \fIname\fR, the location in the search path of the command specified
by \fIname\fR is determined and remembered by the shell. The \fB-r\fR option to
the \fBhash\fR built-in causes the shell to forget all remembered locations. If
no arguments are given, \fBhash\fR provides information about remembered
commands. The \fIHits\fR column of output is the number of times a command has
been invoked by the shell process. The \fICost\fR column of output is a measure
of the work required to locate a command in the search path. If a command is
found in a "relative" directory in the search path, after changing to that
directory, the stored location of that command is recalculated. Commands for
which this will be done are indicated by an asterisk (\fB*\fR) adjacent to the
\fIHits\fR information. \fICost\fR will be incremented when the recalculation
is done.
.SS "csh"
.sp
.LP
\fBrehash\fR recomputes the internal hash table of the contents of directories
listed in the \fBpath\fR environmental variable to account for new commands
added.
.sp
.LP
\fBunhash\fR disables the internal hash table.
.sp
.LP
\fBhashstat\fR prints a statistics line indicating how effective the internal
hash table has been at locating commands (and avoiding \fBexec\fRs). An
\fBexec\fR is attempted for each component of the \fIpath\fR where the hash
function indicates a possible hit and in each component that does not begin
with a '\|/\|'.
.SS "ksh"
.sp
.LP
For each \fIname\fR, the location in the search path of the command specified
by \fIname\fR is determined and remembered by the shell. The \fB-r\fR option to
the \fBhash\fR built-in causes the shell to forget all remembered locations. If
no arguments are given, \fBhash\fR provides information about remembered
commands.
.SH OPERANDS
.sp
.LP
The following operand is supported by \fBhash\fR:
.sp
.ne 2
.na
\fB\fIutility\fR \fR
.ad
.RS 12n
The name of a utility to be searched for and added to the list of remembered
locations.
.RE

.SH OUTPUT
.sp
.LP
The standard output of \fBhash\fR is used when no arguments are specified. Its
format is unspecified, but includes the pathname of each utility in the list of
remembered locations for the current shell environment. This list consists of
those utilities named in previous \fBhash\fR invocations that have been
invoked, and may contain those invoked and found through the normal command
search process.
.SH ENVIRONMENT VARIABLES
.sp
.LP
See \fBenviron\fR(7) for descriptions of the following environment variables
that affect the execution of \fBhash\fR: \fBLANG\fR, \fBLC_ALL\fR,
\fBLC_CTYPE\fR, \fBLC_MESSAGES\fR, and \fBNLSPATH\fR.
.sp
.ne 2
.na
\fB\fBPATH\fR \fR
.ad
.RS 9n
Determine the location of \fIutility\fR.
.RE

.SH EXIT STATUS
.sp
.LP
The following exit values are returned by \fBhash\fR:
.sp
.ne 2
.na
\fB\fB0\fR \fR
.ad
.RS 7n
Successful completion.
.RE

.sp
.ne 2
.na
\fB\fB>0\fR \fR
.ad
.RS 7n
An error occurred.
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
.TE

.SH SEE ALSO
.sp
.LP
.BR csh (1),
.BR ksh (1),
.BR sh (1),
.BR attributes (7),
.BR environ (7),
.BR standards (7)
